Referring to FIGS. 1(a-c), three prior art spark plug boots 10(1), 10(2), and 10(3) are illustrated. Each of these prior spark plug boots 10(1), 10(2), and 10(3) includes a rubber bushing 12, a plastic tube 14, and a rubber cap 16. The spark plug boots 10(1), 10(2), and 10(3) are assembled by gluing the rubber bushing 12 and the rubber cap 16 to opposing ends of the plastic tube 14. A spark plug wire (not shown) is threaded through the rubber cap 16 and into the plastic tube 14. The spark plug wire includes a connector (not shown) which is connected to a terminal end of a spark plug (not shown) when the terminal end is inserted into the rubber bushing 12.
To accommodate different types of internal combustion engines, spark plug boots 10(1), 10(2), and 10(3) typically come in three different lengths, 5.18", 5.88", and 6.26". The length of each spark plug boot 10(1), 10(2), and 10(3) is measured from one end of rubber bushing 12 to the center of an opening in rubber cap 16. The length of each of the prior art spark plug boots 10(1), 10(2), and 10(3) shown in FIGS. 1(a-c) is adjusted by simply changing the length of the plastic tube 14 used.
Although the prior art spark plug boots 10(1), 10(2), and 10(3) discussed above work, there are problems with its design. One of the main problems is that a manufacturer, repair shop, or parts store must maintain an inventory of the three different lengths of spark plug boots 10(1), 10(2), and 10(3) to accommodate the different types of engines. This adds significantly to the overhead costs for these businesses. Another problem is that the manufacture of the prior art spark plug boot 10 is time consuming and expensive because the rubber bushing 12 and rubber cap 16 must be glued to the plastic tube 14 and because multiple tools are required to produce the different lengths of spark plug boots 10(1), 10(2), and 10(3).